technical and economic feasibility of remote area ... · of remote area hydrocarbon exploitation...
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Technical and Economic Feasibility of Remote Area Hydrocarbon Exploitation Using a Clean Energy Producing Vessel
by
Dr Richard Bucknall
The LRET Research CollegiumSouthampton, 11 July – 2 September 2011
‘On the Technical and Economic Feasibility of Remote Area Hydrocarbon Exploitation Using a Clean Energy Producing Vessel’
Richard Bucknall
Marine Research GroupDepartment of Mechanical Engineering
University College [email protected]
Lecture Format
• Energy and Emissions• The CEPV Concept
– Prime-mover Options– Gas Flows and Separation– Electrical Power Transmission Schemes– CO2 Capture and Sequestration– Economic Analysis– Case Studies
• Conclusions
ENERGY AND EMISSIONS
Energy and Greenhouse Gases
Worldwide Energy Supply Today
• Hydrocarbons (oil, gas and coal) supply 87% of our energy needs.
• Nuclear Fission supplies only 6% of our energy needs.
• Renewables supply only 7% of our energy needs and is predominantly large scale hydro-electric schemes.
Today the world uses nearly twice as much energy as it did 30 years ago!
Source: IEA
World CO2 Emissions Today
The worst polluters are:
• Electricity (0.45 kg/kWh)(mixed primary energy)
• Coal(0.35 kg/kWh)(industry and heating)
• Oil (0.27 kg/kWh)(industry and transport)
• Gas (0.22 kg/kWh)(industry and heating)
Electricity – A Worldwide Perspective
• Major contributor to Greenhouse Gas Emissions• Rapidly increasing demand
– Mainly met by new fossil thermal power stations!!!
Source: IEA
Electricity – A UK Perspective
• Major contributor to Greenhouse Gas Emissions• Security of Energy Supply• Future Generation Gap (old power stations)
Type No. of Stations No. of Stations Over 30 Years Old %Gas 19 14 73.7Coal 16 13 81.3Nuclear 12 6 50Wind 66 0 0Hydro 73 61 83.6CCGT 35 0 0Oil 3 1 33.3CHP 5 0 0Other 24 12 50
Total 253 107 42.3
Summary
• There is an ever increasing demand for energy worldwide.
• Electricity consumption accounts for a growing proportion of total energy demand
• Electricity is predominantly generated using hydrocarbon fuels using large (GW) power stations
• CO2 emissions from electricity are a cause of global warming
THE CEPV CONCEPT
Assumptions• Gas is the preferred fossil fuel as it produces less
emissions than coal and oil. Renewables and nuclear are small and likely to remain so.
• UK has its own natural gas resources but is increasingly is dependent on imports.
• Majority of UK gas is offshore. • These also apply to other nations.
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UK Gas Fields
Southern North Sea gas field distribution showing how gas is not in a single large field but is found in many small pockets each requiring its own ‘tap and pipe’.
World Energy Resources
Significant amounts of natural gas is simply uneconomic to recover using pipeline!
The CEPV ConceptClean Energy Producing Vessel
Converter
CH 4
CO 2Subsea Power Cable
National GridInverter
Cable RiserHVDC
HVAC
HVAC
Onshore and Offshore Power Generation
Onshore• Gas is supplied• Gas supply is ‘clean’ gas• Gas is at ‘market price’• Conventional power plant• Housed in a building• Connection direct to NG• Fixed location• CCS requires long pipeline• Known technical solution• Known capital and running
costs
Offshore• Gas must be drilled• Gas supply is ‘raw’ gas• Gas is abandoned i.e. ‘free’• ‘Marinised’ power plant• Housed in a vessel or rig• Connection is via subsea cable• Location not fixed• CCS requires shorter pipelines• Unknown technical solution• Unknown capital and running
costs
Parameter Shore-based Power Station Offshore-based Power Station
Capital Cost Land purchase Power station Connection to gas supply Connection to National Grid Service requirements
Licence to exploit natural gas Wellhead cost and riser Vessel Gas processing plant Power generating plant Subsea transmission cable Connection to National Grid
Running Cost Gas consumption Cooling water charges CO2 emissions tax National Grid connection cost Maintenance cost Manning cost Taxes
National Grid cost Maintenance cost Manning cost Taxes
Cost Comparison
Key parts of a ‘Base Case’ CEPV• Power Generation
– Prime-movers– Electrical generation and distribution– Electrical power transmission
• Gas Side– Well head and riser system– Onboard gas processing plant– CO2 Capture, compressing and storage (optional)
• Platform– Vessel– Ship services– Propulsion (optional)
Prime-movers
STEAM TURBINE
FUEL CELL
DIESEL
GAS TURBINE
Prime-mover Selection Criteria
PRIME-MOVERTYPE
ADVANTAGES DISADVANTAGES
DIESEL Large range of powersCheap £/kWGood efficiency‘Marinised’ engines available
Limited versions use NGHigh maintenance
GAS TURBINES Good power to weight ratioHigh powers availableSome ‘marinised’ engines
Low efficiencyDiscrete size enginesExpensive £/kW
STEAM TURBINES Low maintenanceHigh powers availableRobust and ‘marinised’ plant
Heavy plant (requiresboilers and condensers)Low efficiency
FUEL CELLS Excellent efficiencyLow maintenanceModular construction
Limited versions availableVery expensive £/kWAlmost no use offshore
Combined Cycle Gas Turbine Plant.
High efficiency through waste heat recovery.Exhaust
Power Plant Selected for Base Case CEPV -Combined Cycle Gas Turbine (CCGT)
Specification A 264 MWe Rolls Royce Trent plant which consists of 4 x 51.9 MWe gasturbine generator and 2 x 28.2 MWe steam turbine generator operatingusing the waste heat generator.
Maximum Gas In-Flow Calculations- Intake air: 12.32 million m3 per day- Gas consumption: 1.24 million m3 per day
Maximum Gas Out-Flow CalculationsMinimum Capacity for Base Case CEPV:- Exhaust: 33.7 million m3 per day- CO2: 1.31 million m3 per day
CEPV – Natural Gas Flows
1. A natural gas flexible riser system ‘up-pipe’allows ‘raw’ natural gas to be transferred fromthe wellhead to the CEPV.
2. Gas processing system ‘cleans’ the ‘raw’ naturalgas prior to combustion by the CCGT powerplant.
3. Condensates collected during gas processingare stored for later transfer to a shuttle tanker.
•
‘Raw Natural Gas’
Constituent % Volume Constituent % Volume
Methane 93.00 Hexane 0.05
Ethane 3.00 Heptane 0.03
Propane 0.67 Octane 0.01
Isobutane 0.27 Nitrogen 2.12
Isopentane 0.08 CO2 0.34
H2S 0.43 Condensate 0.05
Typical Constituents in North Sea Natural Gas
Gas Flow Rate
Process flow of gas to exhaust to exhaust and electrical power generation.
GASPROCESSING
PLANT
CCGTGENERATING
PLANT
CONDENSATESTORAGE
CO2 SEPARATION
PLANT
POWERTRANSMISSION
SYSTEM
EXPORT VIASHUTTLE TANKER
CO2STORAGE
NATIONALGRID
CEPV
GASFROMWELLHEAD
AIR
N2
SUBSEACABLE1.31 x 106 m3 / day
6.37 m3 / day
12.32 x 106 m3
1.24 x 106 m3 / day
6.3 TWhrs / day
41 mmscfd
Gas Processing Plant - Wellhead to CCGT Plant
Transmission
CEPV Onshore Station
Generators
Transformer
AC to DC Converter DC to AC Inverter
Transformer
Grid
Transmission Line
• Electrical power conditioning prepares thegenerated electrical power for subsea transmission.• A subsea electrical transmission system connectsthe CEPV to the shore-side electrical grid.
Proposed Bipolar HVDC System
CEPV
G
G
G
G
G
G
VSC
VSC
VSI
VSI
+200 kV
-200 kV
Direction of power flow
National Grid
Onshore
Breaker Transformer VSC – Voltage Sourced Converter VSI – Voltage Sourced Inverter
ICR Cable
Typical HVDC ICR Subsea Cable
Operation mode
Cable type
Voltage (kV)
Conductor material
Conductor CSA (mm2)
Cost (£/m)
Losses (MW/km)
Converter cost (£)
Additional losses
(%)
HVDC ICR 200 aluminium 1000 142 0.051 50 M 5*
Effect of the conductor material and type and voltage operational level in cost of single core cables
0
50
100
150
200
250
300
350
400
450
200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000
Conductor CSA (mm^2)
cost
(£/m
)
200kV copper 200kV alum 250kV copper 250kV alum 300kV copper300kV alum 350kV copper 350kV alum 400kV copper 400kV alum
Cable Costs
CEPV Electrical Power SystemEquipment Specifications Manufacturer
Generators 6 x AC Synchronous BrushlessGenerators operating at 50 Hz and25 kV: 4 x 61.1 MVA 2 x 33.2 MVAVolume : 2,506 m3
GT Generators are suppliedas part of Rolls Royce Trentpackage.ST Generators are supplied aspart of Alstom steam turbinesgenerator package.
Transformers 1 x Step-up Transformer on CEPV
Volume : 630 m3
Siemens Power Transmissionand Distribution
Converters VSC Converter/InverterVolume : 13,000 m3
ABB HVDC Light
Cable type HVDC: 200 kV ICR Cable ICR: Nexans Cables
Generator CircuitBreakers
Water-cooled, continuous currentratings up to 8,000 AVolume : 80 m3
Hitachi GMCB SF6
CLEAN ENERGY PRODUCING VESSEL
DEEP DISPLACEMENT 67,037 TONNES LIGHT SHIP DISPLACEMENT 62,026 TONNES
LENGTH (BP) 179 M LENGTH (OA) 185 M
BEAM (WL) 34 M DEPTH OF HULL 19 M
CP 0.86 CM 0.98
STORES 30 DAYS MAXIMUM COMPLEMENT 20
OPERATIONAL AREA NORTH SEA HULL TYPE MONO-HULL
PAYLOAD
GAS PROCESSING PLANT CO2 SEQUESTRATION PLANT
GAS TURBINE AND STEAM TURBINE GENERATORS SUBMERGED TURRET PRODUCTION SYSTEM
MACHINERY
GAS PROCESSING PLANT ELECTRICITY GENERATING PLANT ELECTRICAL EQUIPMENT OTHER
3-PHASE SEPARATOR
Amine gas sweetener
Glycol dehydration unit
Gas compressor
4X ROLLS ROYCE TRENT GAS
TURBINES AND GENERATOR
2x Alstom WHRU steam turbine and
generator
4x Wartsila diesel generators
1X SIEMENS POWER TRANSFORMER
1x Siemens switchgear
1x Hitachi GMCB sf6 circuit breaker
1x ABB HVDC Light converter station
1X APL SUBMERGED TURRET
PRODUCTION UNIT
1x condensate offloading facility
TANKAGE
CONDENSATE 1,000 M3 SLUDGE AND WASTE OILS 250 M3
FRESH WATER 400 M3 NATURAL GAS BUFFER 900 M3
DIESEL 1 000 M3
CEPV – Outline Design Study
CCS Plant
Equipment Specifications/Requirements CommentsCCGT electricity generating plant
CCGT Plant for Base CEPV: A 264 MWeRolls Royce Trent plant which consists of 4 x51.9 MWe gas turbine generator and 2 x28.2 MWe steam turbine generator.Volume: 11,713 m3
- Intake air: 12.32 million m3
per day.- Fuel consumption: 1.24million m3 per day.- Exhaust Generated: 33.7million m3 per day.
Gas Processing Plant
Gas processing plant to consist of a threephase separator, condensate offloadingfacility, amine sweetener, glycol dehydrationplant, natural gas buffer and emergencyflare.Volume: 13,500 m3
- Minimum gas flow for BaseCase CEPV: 41 mmscfd.- Natural gas required: 1.24million m3 per day.- Condensate production:6.37 m3 per day.1x MAN Turbo Compressor
CO2 Capture and Sequestration
Post-combustion capture with geologicalsequestration into depleted oil and gas field.
Minimum Capacity for BaseCase CEPV:33.7 million m3 exhaust gasper day.1.313 million m3 CO2 perday.
Turret Turret to accommodate: natural gas up-pipe,CO2 down-pipe and cable riser
Natural gas: 41 mmscfdCO2 1.313 million m3 per day250 MWe generatedelectricity
Specification of the Base Case CEPV
CO2 Capture and Sequestration• CCS is a technology under development.• Different solutions for capture are being researched• Different solutions for storage are being researched
Carbon Capture and Storage Schemes
Examples of some current Carbon Capture and Storage Technologies.
CO2 Separation• Separate CO2 from exhaust (Capture process)• Capture processes
– Calcium cycle capture– Cryogenic capture– Amine capture
• CEPV selected ABB-Lummus System– 6,290 m3 of CO2 per hour on a single stream
Transportation of CO2
• The transportation of CO2 by ships is already being done but only on a small scale. Larger ships would be required for the sequestration of CO2
• The CO2 is generally transported as a pressurised cryogenic liquid e.g. at 6 bar and at a temperature of -55 deg. C - energy intensive process.
• The CEPV avoids the need to transport CO2. CO2would simply be transported in short pipelines to a CO2 wellhead.
• Existing technology already in use for CO2enhanced oil recovery. CO2 is easily handled and is large inert, it can be transported at high pressures through pipelines.
• There is extensive pipelines carrying C02 in existence some of which are offshore.
• There are internationally recognised standards for the design, construction and monitoring of pipelines carrying CO2 offshore and onshore.
CO2 Sequestration
CEPV Economic ModelInput Page: Output Page:
• CAPEX, OPEX • IRR, PP, NPV
Data Collection(Input Page)
CAPEX Calculation
Timetable Calculations
Revenue and OPEX
Calculation
Calculation of IRR and PB
Presentation of Results
(Output Page)
• Financial information• Plant Technical Data• Field Information Data• Transmission Data
Input Page
Output PageGas-to-Wire
CAPEX
Vessel Basic Vessel 66.3 (all £M) Generator Set 153.7 Sequestration Plant 0.0 Electrical Equipment 44.2Platform Structure - Processing Plant -Wells and Subsea Installation 56.1Risers (Dynamic) 2.8Transmission Cables 57.5Pipeline -Onshore Electrical Equipment 44.2Connections 0.1Miscellaneous 0.0Relocations 0.0Decommissioning 12.7
Total 437.4 £M
OPEX First year 17.3 £MTotal 258.4 £M
REVENUE Revenue per year (max.) 98.5 £MGross Revenue 1477.2 £M
IRR Post Tax 13.97 %Pre Tax 19.42 %
NPV NPV at 5% 241.1 £M
PAYBACK Payback Period 6.6 years
Results: Impact of Electricity Sales Price
• CEPV demonstrates satisfactory payback and IRR provided electricity price is about £60/MWhr
• An upward trend of electricity price is desirable to ensure profitability
05
101520253035404550
20 30 40 50 60 70 80 90 100
Electricity Price (£/MWhr)
IRR
(%)
Post TaxPre Tax
0
2
4
6
8
10
12
20 30 40 50 60 70 80 90 100
Electricity Price (£/MWhr)
Payb
ack
Perio
d (Y
ear)
Impact of Distance of Shore and Water Depth
• Generally, further offshore means greater depth and increased costs for cable and up and down pipes.
• However the impact on IRR and payback is modest.
0
5
10
15
20
25
25/40
50/50
75/60
100/7
012
5/80
150/9
017
5/100
200/1
1022
5/120
250/1
3027
5/140
300/1
50
Distance from Shore (km)/Depth (m)
IRR
(%)
Post TaxPre Tax
012345678
25/40
50/5075
/6010
0/70
125/8
015
0/90
175/1
0020
0/110
225/120
250/1
3027
5/140
300/1
50
Distance from Shore (km)/Depth (m)
Payb
ack
Perio
d (Y
ear)
0
10
20
30
40
50
0 2 4 6 8 10 12 14 16
Year
0
2
4
6
8
10
12
0R2W 1R2W 2R2W 3R2W
x Relocations and x Wells UsedR = Relocations, W = Wells Used
Payb
ack
Perio
d (Y
ear)
Impact of Relocations
0
5
10
15
20
25
0R2W 1R2W 2R2W 3R2W
x Relocations and x Wells UsedR = Relocations, W = Wells Used
IRR
(%)
Post TaxPre Tax
• Increasing the number of wells allows increased gas flow as the gas field depletes but is more expensive.
• Increasing the number relocations (which will include down time) means reduced IRR and increased payback.
Economics of CO2 Sequestration
• The impact of using CO2 Sequestration was found to be detrimental to the economic viability of the Base Case CEPV without CO 2 CCS.
• Further studies looked at the level of subsidy required and/or Carbon Tax to make the CEPV with CO2 Sequestration economic.
Parameter Without CO2 Sequestration With CO2 Sequestration IRR (%) 19.42 (13.97) 6.27 (3.28) PP (Years) 6.6 11.7 NPV (£M) 241.1 -57.3 CAPEX (£M) 437.4 595.3 First Year OPEX (£M) 258.4 327.7
Gen Set Output (MWe)
η (%)
Total NG req. per
day (tonne)
Minimum gas flow to
achieve maximum production (mmscf/d)
Total NG
prod. per day (tonne)
Volume of NG prod.
per day (million
m3)
O2 req. per day (tonne)
Volume of
intake air req. per day (million
m3)
CO2
prod. per day (tonne)
Volume of CO2
prod. per day (million
m3)
1 258 37 1244 64 1256 1.76 4990 17.52 3481 1.872 250.8 51 877 45 883 1.24 3508 12.32 2447 1.313 502 52 1722 88 1726 2.42 6861 24.09 4786 2.574 279 52 957 49 961 1.35 3820 13.42 2665 1.435 264 54 872 45 883 1.24 3508 12.32 2447 1.3136 267 51 934 48 942 1.32 3742 13.14 2611 1.47 263.2 54 869 45 883 1.24 3508 12.32 2447 1.3138 157 54 519 27 530 0.74 2105 7.39 1468 0.799 264 54 872 45 883 1.24 3508 12.32 2447 1.31310 328 49 1194 61 1197 1.68 4756 16.7 3318 1.77911 400 54 1321 68 1334 1.87 5302 18.62 3698 1.9812 502 52 1722 88 1726 2.42 6861 24.09 4786 2.5713 259.5 42 1102 57 1118 1.57 4444 15.61 3100 1.6614 258 55 837 43 844 1.18 3352 11.77 2339 1.25
Power Plant and Generator Set Options
0 5 10 15
12
345
67
89
101112
1314
CEPV
Sce
nario
PP (Year)
With CO2Without CO2
Case Study – Clair FieldClair
Platform
Power Station on Shetland Islands
Magnus Field(Re-injection)
Natural Gas
CO2
Sullom Voe (Shetland Islands)
Oil
CEPV
National Grid at Dounreay, Scotland
Electricity
Supplementary Natural Gas from ‘Cap’
Original Natural Gas Arrangement
0123456789
10
8 9 10 11 12 13 14 15
Period of CEPV Operation (Year)
IRR
(%) 30 mmscf/d
25 mmscf/d20 mmscf/d
Clair Field is West of Shetland and ismainly an oil field with natural gas.
Case Study – Bonga Field Bonga
FPSO
Nigeria LNG Ltd. in Bonny, Nigeria
Natural Gas
CO2
Export to market via shuttle tankers
Oil
CEPV
Nigerian National Grid at Aladja
Electricity
Bonga Field
EOR
Options CAPEX (£M) OPEX (£M) NPV (£M) IRR (%) PP (Years) Power Gen. (MW) Power Exp. (MW) Viability Ranking1 521 118.1 31.4 6.46 7.4 258 245.1 Y 32 601.3 132.8 -124.2 0.05 - 250.8 238.33 934.2 210 30.7 5.79 7.6 502 476.9 Y 44 643 144.9 -112.5 0.57 9.7 279 265.15 601.8 218.7 -158.3 - - 264 250.86 537.8 117.9 -31.7 3.51 8.4 267 253.77 535.1 109.4 -79.2 1.25 9.3 263.2 250.08 560.9 193 -288.6 - - 157 149.29 601.8 218.7 -158.3 - - 264 250.8
10 654.1 151 -5.5 4.77 7.9 328 311.611 695.1 166.4 91.6 8.16 8.66 400 380.0 Y 212 833.3 203 127.1 8.64 6.8 502 476.9 Y 113 542.7 188.3 -48.4 2.74 8.7 259.5 246.514 557.3 125.3 -71.5 1.76 9.1 258 245.1
Conclusions• If the world is serious about reducing global
warming through a reduction in emissions then it must either reduce its dependence on fossil fuels or learn to avoid emitting CO2 into the atmosphere.
• Energy sources are becoming more remote –much lies offshore in remote locations known as stranded gas reserves.
• The CEPV is an offshore power concept that appears technically and economically feasible for exploiting some stranded gas reserves
• The CEPV with CO2 Sequestration requires subsidy to make it economic although technically feasible to achieve.